The compounds: 11-trimethylsilyloxy-1,2,3,4,4a,9a-hexahydro-1,4-etheno-anthraquinone and 4-benzyl-8-trimethylsilyloxy-4-aza-tricyclo[5.2.2.0]undec-8-ene-3,5-dione were synthesized by the Diels-Alder [${}_4\pi_s +_2 \pi_s$] cycloaddition reaction of 2-(trimethylsilyloxy)-1,3-cyclohexadiene with naphthaquinoneand 𝑁-benzylmaleimide under ultrasonic conditions. The crystal structure analysis was done using single crystal X-ray diffraction method. In both the compounds, the trimethylsilyloxy- and naphthaquinone/𝑁-benzylmaleimide moieties are endo- to the bicyclic ring.
